Shouldn't the unsent draft be dated on 6 Sept 1957, as said in Chronology? TCG doesn't seem to have the 1957 one listed, unless #915 is meant to be it.
Anyway, now you ref #915 to Chronology p553, and #1100 to RG p 20-2. But the quote in Chronology p553 is identical to that in RG p 20-2, and S&H appear to suggest they are the same thing.

zionius wrote:

Shouldn't the unsent draft be dated on 6 Sept 1957, as said in Chronology? TCG doesn't seem to have the 1957 one listed, unless #915 is meant to be it.
Anyway, now you ref #915 to Chronology p553, and #1100 to RG p 20-2. But the quote in Chronology p553 is identical to that in RG p 20-2, and S&H appear to suggest they are the same thing.

I have not reached 1957 yet (currently on mid-20s) so details may very likely be updated re. dates later, and letters merged.